Throughout the life course, the constellation of people with whom an individual resides (i.e., his coresidents) changes. Previous research on this phenomenon has been hampered by (1) the lack of continuous longitudinal data on people's coresidential experiences, and (2) the use of the household and the family as units of analysis. Ideally, we need to trace individuals through time in an unbroken stream, a longitudinal approach not possible in analyses relying on census and vital registration data sources. Moreover, by focusing on the household or the family, the analyst is using a unit which has no truly longitudinal existence. Benefitting from the almost unprecedented wealth of continuous coresidential and demographic data recorded in the Italian population register (together with data from municipal and parish vital registration records, parish censuses, and manuscript cenuses), this study is designed to shed new light on the life course processes of coresidence. The interrelationships between coresidential circumstances and fertility, marriage, mortality and migration will be examined through the study of a rural Italian commune experiencing industrialization (1865-1911). By focusing on the behavior of individuals through time, and by comparing cohorts, characteristic patterns of coresidential experiences through the life course will be elucidated and changes in these patterns in response to early industrialization examined. Toward this end, historical research will also be conducted in order to identify the changing economic and social forces which affected people's choices of coresidential arrangement through their life course.